Air and Water – Who Needs It?

By Amanda Streets

I was up extra early this morning to turn my pile. I’d been avoiding it all week. It’s unseasonably hot this week, even for Florida, and dry as a bone. But, my compost needs some TLC so out to the pile I went, pitchfork in hand.


What’s the big deal… why all the fuss? Compost happens… right? Do you really need to turn it?

The short answer is that yes, compost happens and will eventually happen without turning it. But is it the best way to compost? No.  I made this big heap of compost in my yard and I’d like to use it in my gardens sooner rather than later. And I’d like it to be as rich as possible in both nutrients and microbial life.

Simply put, your compost is an incubator for all sorts of tiny organisms that actually do the work on composting for you. They just need to be kept happy with the right balance of basic needs. Happy soil life, happy compost, happy plants.

The Air

Imagine holding your breathe for a few minutes? That gets pretty tough, doesn’t it? Just like you and I need air to live, your compost organisms do too. You can get more air into your pile by turning it with a shovel or pitchfork, or by giving your tumbler a spin. Alternatively, you could add large chunky branches and pieces of carbon to your compost. This will help get moreĀ air by creating spaces but some areas may still become oxygen-deprived. A quick fix is to put long PVC pipes with holes drilled in them into your compost pile with the ends sticking out the sides and top. The breeze will blow into those pipes, bringing it to more places in your compost. Many commercial compost sites avoid turning by aerating the piles with large blowers. The pipes I suggested above are an easy, low-tech way to mimic that.

Without air, your microorganisms start to die and your compost will become anaerobic, meaning organisms that don’t need oxygen to breathe will start to grow. The anaerobic organisms produce smelly gasses. No one wants a smelly compost pile including your garden.  A properly composting pile should smell like rich soil from the forest floor, not like alcohol, formaldehyde, rotting flesh or ammonia. Anaerobic conditions are also evident by a white ashy powdery layer in the compost with a dark black layer below it.

If you go to turn your pile and unpleasant odors waft out, it’s not the end of the world. Turn your pile, and make sure the moisture level is adequate and continue composting. If you have some good rich aerobic compost from a previous pile, add a few shovelfuls to help the good organisms get a jump start again. If not, it’ll be fine.

The Water

It may be tempting to just water your compost from the top. While this does add water to parts of the compost, it won’t be evenly moist. Dry pockets will be sure to form. Running the water longer probably won’t help either, since it’ll take the path of least resistance and go straight out of the pile. You’ll end up with a compost pile on top of a mud puddle.

Just like air, soil organisms need water. A dry compost pile won’t really compost until it gets moisture. When it’s too dry, the organisms actually die or go dormant. That means they aren’t working to make that compost for you. You’ll want to take care of those little critters so that you can use the compost.

just right compost
This compost is just right. 

When you build your compost pile, try to make it evenly moist, at about 50 or 60% water. A good way to tell is by doing The Squeeze Test. Take a nice handful of compost and squeeze it in your fist. If it clumps together like play dough, that’s perfect. This same squeeze test applies for each time you turn your compost too. Check it and water accordingly while you are turning it so water gets to all parts.

If water squeezes out between your fingers, it’s too wet. To remedy it, you can turn your pile to mix it up and add a little more carbon to soak up the moisture. A good way to prevent it getting waterlogged is to make sure you cover it, especially during a rain storm (unless it’s really dry).

compost dry

If it falls apart in small pieces or is powdery, that’s too dry. Turn it and water it at the same time. You might be surprised at the amount of water it will take to re-saturate a dry pile.  Just add the water, it’s important. If it was really dry, you might even consider adding water and turning half the pile, waiting a bit and re-wetting the pile, mixing up the already turned portion and checking it again for moisture, then finish turning it while continuing to water. Dry compost will repel the water at first, becoming hydrophobic just like sand.  If you cover the compost pile, it’ll help retain the moisture that is lost during evaporation. Just remember to check the moisture levels every week and uncover during the rain if it’s dry between turning (your compost organisms LOVE rainwater!)

Remember, if those soil organisms are happy, your compost is too. Try to manage the air, water, and ratios of green and brown materials and you will be successfully composting every time.


Young Professional May 2019 The New Composter Webinar Series Part 2, US Composting Council.

Photo Credit:

Published by Pinellas Community Composting Alliance

Pinellas Community Composting Alliance was formed as an education and advocacy group to promote community composting in our Tampa Bay area. We do this by holding classes, helping to establish community compost drop off stations, and working with others to help create a more sustainable local food system.

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